Below you can find Sitebuilder support team answer concerning this question:

We know about this situation with page names and already submitted feature request to our developers team. But I can't say exactly when this feature, renaming pages to more appropriate names, will be implemented in Sitebuilder. I can say exactly that nearest update won't contain this feature

They just told me that it's NOT planned for the next update, but it should be in the next version - Sitebuilder 3. Sigh

Until then, I'm considering writing a script that will allow clients to view all the pages they just generated, and changing the page names according to page titles (or their own choices). Has anyone done that already?